Polymarket and Kalshi on the same bitcoin strikes, captured once an hour (at :12 UTC): the price at which the crowd calls it a coin flip, and how far the two crowds disagree.
$81,081 the coin-flip price · both venues · Kalshi on Oct-22 2026, the last day in this build, measured and published by askthetape.com.
Two regulated betting venues let people buy a contract that pays a dollar if bitcoin is above a given price at the moment it settles on a given day. The price of that contract is a probability, in public, updating all day. We record both venues on the same strikes once an hour, so you can ask two things no single venue answers: what price the crowd calls a coin flip for the contracts that settle that same day, whatever their hour, and whether the two crowds disagree with each other. On the board that settles the SAME day — the only one this page reads — Kalshi quotes about 250 strikes a day and Polymarket about 11.
| leg | own capture of the Polymarket and Kalshi order books (file feed `xvenue_*`), last quote of the UTC day per venue × target day × strike |
|---|---|
| 🩸 which hour a day's odds belong to | the contracts pooled into one day do not settle at one moment: on Oct-22 2026 the Kalshi contracts behind this row settle at 19 different hours of that day, New York time, next to Polymarket's own same-day contract, and since Sep-12 2026 Kalshi has listed ten or more settlement hours a day. The coin-flip price is read across all of them, so it is not the price of any single close, and part of the gap between the two venues can be a difference in settlement hour rather than a disagreement. |
| cadence | once an hour at :12 UTC, daily view |
| since | 2026-07-17 · BTC strikes only |
| policy | the coin-flip price is an interpolation between the two neighbouring strikes whose quotes straddle 50 %, computed only on contracts whose settlement day IS the row's day (target_day == date) — no longer-dated strike enters it. 🩸 that condition used to be «one day or less to expiry», which let tomorrow's board in: 47.7 % of that pool settled on another day, which doubled the strike counts (Kalshi 467 a day instead of 250) and moved the coin-flip price. Every row keeps bid, ask and mid, so a wide spread shows up as width rather than hiding inside a mid. · export: whole history |
| gaps | measured on this leg, not assumed: the line has no point on 2026-07-18 … 2026-07-19 (2 days) on Polymarket; 2026-08-02 … 2026-08-03 (2 days) on Polymarket; 2026-08-21 … 2026-08-23 (3 days) on Polymarket — it BREAKS there and nothing is drawn across it |
| hourly window | prod file feed ~/tradfi_poller/data/xvenue_*.jsonl, our own hourly capture of both books (at :12 UTC) · since 2026-07-17 11:00Z by data, 2,265 hours with data inside a 2,363-hour span → 2026-10-23 21:00Z (the Tape and Desk windows draw up to 400 days of that, never more than we hold) · captured 2026-10-23T21:21:56Z |
| this build | data to Oct-22 2026 |
| policy | no backfill · read it here · export: whole history |
The chart itself is drawn in the browser: turn JavaScript on to hover a day, pick a window and draw your line. The numbers above come from the last build, Oct-23 2026 21:24Z.
What the tape says today · what's new · all 111 metrics